Many clay deposits often need to be stabilized before they can carry any additional load such as is applied during filling and construction activities. This is specially true for the so-called quick clays which frequently are found, for example, in northern Soviet Union, Scandinavia, Canada, upper New York State, and New Zealand. Clays were originally deposited in marine and brackish water in a short period after the last glaciation, and later during the continental (isostatic) uplift were raised above sea level. However, only certain of these clay deposits were subsequently changed into sensitive quick clays. Two processes are mainly responsible for such a change. The original pore water salt content of the clay may have been leached by percolating ground water, or organic matter from logs or marshes which will act as dispersing agents may have been introduced into the clay. The first process has been most important in clays found in Norway, while quick clays containing high organic content formed by the second process are frequently found in Sweden and Canada.
The quick clays will in the undisturbed state exhibit a certain limited strength, but will upon remoulding completely liquify. This same phenomena has caused several quick clay slides in the lowlands of eastern and middle Norway, often with catastrophic consequences. Heretofore, several chemical stabilization schemes have been tried for such clays. Among them were aluminum chloride (AlCl.sub.3) and potassium chloride (KCl). The quick clays have been stabilized in two ways. The clay can be mixed and remoulded with the chemicals, or the chemicals can be allowed to diffuse into the undisturbed quick clay. The disadvantage of the salt diffusion method is the long time it takes to reach the required penetration. The diffusion method has been applied only once, so far as is known, in full scale in the field, when salt wells containing KCl were installed two years prior to a major highway construction.
One method for deep stabilization is the infusion of unslacked lime (CaO) into the soil. Lime is an old stabilizing agent that was used centuries ago as a construction material. In the U.S.A. in the 1940's and Europe in the 1950's lime was used as a surface stabilizing agent. The deep stabilization method involves mixing and molding the lime with the clay to form a series of piles which extend down into the clay. These piles provide lateral stabilization to the clay deposit.
Hydroxy-aluminum [Al(OH).sub.2.5 Cl.sub.0.5 ] alone and in combination with chemicals such as potassium chloride (KCl) is disclosed as a clay stabilizing agent in U.S. Pat. No. 4,360,599 issued to Tor Loken and Odd R. Bryhn on Nov. 23, 1982. The same patent describes the need for proper admixing of the stabilizing agent into the clay in order to achieve the desired results. Some stabilizing chemicals such as hydroxy-aluminum have more stringent mixing requirements than unslacked lime. Existing mixing devices and methods are functional but do not consistently provide the precise mixing required to produce desired results. There still is a need for an improved method and device for properly mixing stabilizing chemicals into clay soil.